Not particularly pleasant to watch. The events at the heart of this movie are supposed to be thought of ambiguously, as maybe not such a big deal. I don't know about 1988 Boston, but I live in the South in 2005. I think that here and now, if these sort of things came to light, there would be a lot more going on than a custody dispute. Probably a major criminal investigation, at minimum. Anyone has the right to live a bohemian or libertine lifestyle, but not necessarily the right to subject children to such things.
The movie could have developed the character of the ex-husband a bit more. As it stands you really don't know if his motivations are reasonable concerns about his child, or if he simply intends to stick it to his ex.
Everything else about the film, aside from the material was just fine. The lead acting, the child actor, Leonard Nimoy's direction were all good. Katey Sagal was good and looked scrumptious in a small part.
Worth checking out if you are willing to forgo the car chases and alien wars, and think about something. But don't expect to enjoy it.